A problem that has arisen with the advent of artificial turf when used as playing surfaces in outdoor sports areas is that the artificial surface becomes extremely hot. This problem also exists with some forms of tennis courts, for example outdoor hard surface courts, where the playing surface is often of a dark heat-absorbent color. The heat from such surfaces is quickly transmitted through the sole of a conventional athletic shoe to the foot of the wearer to his discomfort.
Cushioning insoles comprising a composite fabric made up of two woven fabrics separated by a corrugated fabric have been proposed for use in shoes to provide thermal insulation. See for example the composite fabric described in U.S. Pat. No. RE 24,007. The composite fabrics as disclosed in that patent are described as being compressed to 30% under a loading of 2 psi. Where a composite fabric is used as an insole, the loading, assuming a wearer of between 90 and 180 pounds, will vary between 16 and 32 psi at the ball area of the foot and be even higher at the heel area. These high loadings will cause movement of the two woven fabrics of the prior art composite fabric towards each other flattening out the corrugated separating fabric. Any air channels that might exist in such fabric due to the corrugated separating fabric are substantially reduced or even completely eliminated so that any thermal insulation due to the air in the corrugated channels or cooling due to circulation of air through the corrugated channels is materially reduced. It is therefore an object of our invention to provide for shoe material which may be included as an insole in shoe constructions when originally manufactured, or sold and applied as a separate item to existing shoe constructions and which will provide a cooling non-collapsible air circulation space between the bottom of the foot of the wearer and the sole of the shoe under high load conditions as occurs at the ball and heel areas of a sole of a foot.
A further problem existing with some forms of athletic shoes, as for example track or marathon shoes, is that the friction between the shoe body and the foot of the wearer adds to the heat in the shoe and that the body of the shoe tends to retain perspiration all adding to the discomfort of the wearer. It is therefore a further object of our invention to provide for a shoe material that may be utilized as the uppers for shoes and at the same time provide for a high degree of air circulation surrounding the foot of the wearer to aid in cooling and to aid in the evaporation of perspiration.